And the British and the Japanese.
But more importantly, nor do you.
I get ya. Good luck changing the way that millions of people have done for hundreds of years because you have your own definition.
Carry on.
And fwiw, if i wanted to talk about the kind of military personal who fight on land, I’d probably go with “infantry”, although i guess “cavalry” has been replaced by people who ride in motorized vehicles (tanks, cars, anything in between) so infantry is not a super word.
Such as members of the Merchant Marine.
That would be rather like calling everyone who works in a hospital “doctor.”
I don’t think so, that’s what the army does, calling chaplains and system analysts “soldier”. I think it’s more like using “doctor” generically to include MDs, osteopaths, veterinarians, nurse practitioners, EMTs, and other people who are in the front line of delivering medical care.
Soldier of Fortune
Soldier of God
Animal doctor
These are both generic words as well as specific words
Interesting. I have no military background, but I wouldn’t have thought of “soldiers” as a general term for all military members. Maybe due to my deep historical research into the tomes of Professor Forester. 
The rule at MIT used to be:
If he’s wearing a tie, call him “Professor.”
If he has a beard, call him “Dean.”
When in doubt, call him “Doctor.”
It may very well be that something is getting lost in translation, but this WELT documentary on YouTube refers to the crew of German submarine as “soldiers”.
And you miss out on the artillery, which is not part of the infantry.
And for cavalry there is not just trucks but also the helicopters, the air cavalry.
And APCs. And IFVs/CFVs.
Marines used to have “cavalry:” horse patrols to guard naval bases and larger embassies. They also had Abrams tanks until 2020.
Systems analysts might be soldiers, but chaplains and most medical personnel typically are not. They even get a different version of their military ID card—which also serves as a Geneva Conventions identification card—indicating they are noncombatants. People serving in noncombatant roles typically advertise this with a Red Cross (as with USNS hospital ships or MASH units). Noncombatants are permitted to defend themselves and their patients, but must not engage in offensive operations.
(The situation is a little more blurry with medics and corpsmen on the battlefield. They are non-combatants if they are performing a medical role, but they carry weapons to defend themselves and do not display a Red Cross. And If they join in any offensive operations, they forfeit their noncombatant status.)
I find it pretty odd that anyone, even someone not versed in military terminology, would call someone serving in the Navy a “soldier”.
I mean, even little kids have heard of Popeye the Sailor, who joined the U.S. Navy in 1941 and wore a Navy uniform for decades thereafter.
Well, Popeye was obviously a sailor. And i don’t think it was ever obvious he was a military sailor, at least, i never knew that as a kid watching the show. (See my comment above about my being a mediocre sailor)
But even if I’d known he was in the Navy, and thought that he was also a soldier, that’s like saying that an apple is a kind a fruit. IMHO.
And yet, for some reason, people want to call marines (tangerines) a kind of soldier (apple).
Maybe the closest analogue is people who call all carbonate soft drinks (soda) coke. Pepsi might be a kind of “coke” to you, but your use is idiosyncratic.
There’s “Soldier” as a proper noun, meaning someone in the US Army, and then small-s soldier, meaning a member of a country’s armed forces.
Sailor is even more odd, in that small-s sailors can mean the people on “Below Deck”, not just military sailors.
US Navy personnel are generally not soldiers. Most of don’t touch hand held weapons, a few man really big guns. There are a few exceptions like Seals and sometimes Seabees, but generally, we’re not soldiers and have less training in gun use and hand to hand fighting then most southerners.
Onboard carriers, we actually have a small Marine detachment, so not even the Master-at-Arms have firearms, at least most of the time.
Generally not. Like @What_Exit was saying. Not even for the Air Force.
Cite?